Beams:

A beam is a structural member of adequate length compared to lateral dimensions & supported so as to be in equilibrium & usually, subjected to a system of external forces to generate bending of the member in an axial plane. Ties, shafts, struts and beams are all one-dimensional or line-elements where the length is much greater than the depth or width. These are also known as skeletal elements or rod-like; and have different names depending upon the major action they are designed to resist. Therefore, ties & struts resist uniaxial tension or compression, shafts resist torque & beams resist bending moments (and shear forces).

The apparent horizontal distance among the supports is called as the clear span of the beam. The horizontal distance among the centers of the end bearings is called as the effective

span of the beam. If the intensity of the bearing reaction is not identical, the effective span is the horizontal distance among the lines of action of the end reactions.

                                    Figure: Clear and Effective Spans in a Beam

Whenever a horizontal beam is loaded, it bends because of the action of loads. The amount with which a beam bends, based upon the amount and kinds of loads, length of the beam, elasticity properties of the beam material & the type of the beam.

Beams might be concrete, steel or even composite beam, along any type of sections such as angles, channels, I-section, hat section, square, rectangle etc.